Yes, anxiety is common - if not almost universal, after quitting. Having said that, it's also entirely possible that you suffer from GAD or a variant of it - it's a very common issue. If you cant' get a handle on it on your own, consider seeing a counselor - it's a very treatable and common condition.
Some of the standard things to look at are caffeine intake ( cut back or cut out completely ), sugar consupmtion, diet, exercises, sleep, etc.